This invention relates to a cutter for a shaper and, more particularly, to a cutter for cutting irregular shapes such as teeth of a gear. Customarily, such cutters include a body with a plurality of teeth spaced angularly around the periphery of the body. The ends, sides and roots of the teeth are inclined radially inwardly from the face of the body so that the edges of the teeth constitute the cutting edges of the cutter. The cutter body is, in turn, clamped to the spindle adapter on the machine.
Frequently, the cutter is surface coated with a thin film of titanium nitride in order to enhance its life. When the cutting edges of most present commercially used shaper cutters become dull, they are resharpened by grinding the face of the tool and hence the faces of the teeth. Such grinding presents a number of difficulties. For one thing, because the ends, sides and roots of the teeth are inclined, the grinding changes the relationship between the cutter and the workpiece and thus the original setup of the cutter in the machine. Consequently, the original setup of the cutter and the work must be adjusted to compensate for this. Also it is difficult to achieve a high quality of sharpening as compared with the sharpening performed at the point of manufacture. In addition, where the cutter is coated, the cutting edges and surfaces are no longer coated after grinding.
My prior U.S. application Ser. No. 615,775, filed May 31, 1984, now U.S. Pat. No. 4,576,527 discloses a shaper cutter which overcomes the foregoing problems. In the cutter disclosed in that patent, teeth with cutting edges are formed on a thin flexible wafer which is attached to and conforms with the teeth and face of a tool body, the latter being basically the same as the cutting body of prior cutters and serving to back the cutting teeth of the wafer. When the cutting edges become dull, the thin wafer is simply removed and replaced with a new one. To attach the wafer to the tool body in conformity with the teeth and face thereof, provision is made of a clamping ring adapted to lie against the end face of the wafer. When a fastener is tightened, the clamping ring flexes the thin wafer into conformity with the tool body and clamps the wafer and the body in assembled relationship.
In the cutter of U.S. Pat. No. 4,576,527, the clamping ring projects ahead of the wafer and creates a potential source of axial interference when the cutter is advanced through its cutting stroke.
In addition, as noted previously, the tool body is clamped to the spindle adapter of the machine. The clamping force thus being exerted also subjects the clamping ring shoulder, which flexes the insert against the cutter body, to high shear stresses and potential fracture.
My prior U.S. application Ser. No. 827,648, filed Feb. 10, 1986 which issued as U.S. Pat. No. 4,673,317 on Jun. 16, 1987 addressed the above shortcomings by a new design where the wafer is bonded to the face of the tool body by a high strength adhesive. When the teeth of the wafer become worn, the cutter assembly is heated to a high temperature to destroy the bond and enable the removal and replacement of the insert. Although this design is functional, the procedure for insert replacement has been proven to be time consuming and cumbersome. Particularly the heating of the cutter assembly and the subsequent cleaning of clamp and cutter body, were found to be non cost effective operations in a production environment.
Another design of a disposable shaping tool is the subject of the Tlaker et al U.S. Pat. No. 4,629,377. The disposable flexible disc of this design has the basic configuration of a spur gear and consequently can be used on both sides. When clamped, the flexible disc is deflected to a negative rake angle, thereby creating the required clearance angles on the cutter teeth. The negative rake angle however tends to inhibit chip flow, which increases tool wear. Also it is not practical to use this tool for any typical shaping applications which require shaping against a shoulder where interference with the axially protruding clamp elements would exist.